The haskeem package

This is a moderately complete small scheme interpreter.
It implements most of R6RS, with the exception of call/cc.
It is however starting to have a set of delimited
continuations, reset/shift et al. It has a macro system,
although not R6RS hygienic macros. It is also not
necessarily fully tail-recursive; so it's not
industrial-strength. For playing with or learning scheme,
it should be pretty good.